A shredding/crushing machine, which is the subject of this invention, is shown in FIGS. 23, 24 and disclosed in, DE 42 42 740 A1. The machine is used for cutting and reducing wood, metal parts, plastic material, garbage and other waste materials to small pieces.
The shredder/crusher 101 essentially consists of a material hopper 102, a food unit 103 and a cutting tool 104. The three machine components 102, 103, 104 are connected to one another so as to be detachable by flanged couplings and, when assembled, form a feeding chamber 105. In the feeding chamber 105, a cutting shaft 106 driven by an electromotor engages in this lower area opposite the feed unit 103. The cutting shaft 106 is octagonal or polygonal in shape and is equipped with a number of cutting tools 107. The cutting tools 107 are fastened to the cutting shaft 106 spirally wound and distributed over the periphery (FIG. 23) and are engaged with a first cutting plate 108 and a second cutting plate being used as a scraping bar. The upper side of the first cutting plate 108 is simultaneously part of the floor of the feed chamber 105. A perforated screen 111 fastened to reinforcing rings 110 is fastened below the cutting shaft 106. A collecting tray 112 is situated below the screen 111, a worm conveyor 113 being connected to the lowest point of said collecting tray for removing the shredded/crushed material. FIG. 10 shows the cutting shaft 16 in a perspective of a partial view, as seen from the feeding chamber 105. The cutting shaft 106 has a number of cutting tools 107 which are attached to the cutting shaft 106 in a thread-like manner. The cutting tools 107 sit in the recesses 129 placed into the cutting shaft 106. The recesses 129 extend from a first edge 140 or the cutting shaft 106 to the second edge 141 following in direction of rotation. The base 142 of the recess 129 deepens uniformly relative to a cutting shaft surface 139 over its entire longitudinal extension. The base 142 or the supporting area 131 forms a right angle with the contact surface 131. The height of the contact surface 131 between the second edge 141 and the base 142 corresponds to the diagonal extension of a cutting tool 107.
The knives 104 which are square in cross section are arranged on the shaft 106 so as to be in a diagonally upward position and form a cutting edge 107a in the shape of a pointed roof with a cutting point 107b protruding upward.
A shredder/crusher of this type has proven successful.
In the field of waste recycling and disposal of waste materials, disposal firms must respond more and more flexibly to the various materials to be processed. Thus, for example, not only hard materials such as plastic housings, plastic products, electronic parts or other breakable materials have to be shredded or crushed, but also stretch materials, woven synthetic materials, carpets, threads and fibers of all types. In addition, the material to be cut often varies considerably in size and volume; for example, small-sized hollow plastic bodies (PET bottles) and plastic barrels must be handled. Experience has shown that unsatisfactory results are often obtained with respect to the cutting work when using preset a driving power for the cutting shaft and a preset size for the cutting tools.
DE-GM 295 15 768.2 discloses cutting tools for shredding machines. The cutting tools consist of several parts, having a cutting tool body and one or two cutting plates. The cutting tool body is an elongated one-piece metal body having, for example, a square cross section, two front surfaces and four similar lateral surfaces. The cutting tool body is somewhat shorter than the cutting tool shown in FIGS. 1 and 2. At the front surfaces, a longitudinally axially tapped hole is placed in the canter into which a screw can engage to fasten a cutting plate. The front surfaces have a contoured surface with two cross-shaped grooves which each extend between the points of the front surfaces.
The cutting plates are thin metal plates which can have a corresponding square shape like the front surfaces of the tool body. A hole, through which a fastening screw can pass, is placed in the centre of the cutting plates. On their back side, the cutting plates have webs arranged transversely which are adapted to the shape of the grooves of the cutting tool bodies so that the cutting plates can be fastened in a form-locking and torque resistant manner to the front surfaces of the cutting tool bodies.
The cutting tool bodies, each having a cutting plate, form a cutting tool which has the same spatial shape and the same dimensions as the one-piece cutting tool of FIGS. 23 and 24. All four points of the cutting tools can be used as a cutting point, so that a cutting tool with two cutting plates can be used eight times.
Cutting tools of this type have proven successful. However, it was found that, with a set cutting tool size of e.g. 40.times.40.times.64 mm, it is not possible to efficiently obtain a defined granular, size, in particular of lose than 10 mm. Although an increase in rotational speed and an even larger number of knives on the knife shaft can lead to an increase in cutting speed and a higher cutting sequence and, as a result, a fine granulation, however, this also causes friction and heat, especially in the area of the screen basket area. Moreover, additional suctioning devices are required that draw off the fine material through the screen basket area by suction and prevent unnecessary material rotation about the shaft body and a decrease in throughput. In addition, it was found that, in PVC or stretch foils having a low melting point, the heat formation can be so high that it can result in melting of the material and blockages in the cutting system.
The object of the invention is to create a cutting shaft for a shredding machine which can easily and quickly be optimally adjusted to the material to be cut and, moreover, to provide a cutting tool with which it is also possible to produce defined, in particular, small granular sizes without thereby altering the quality of the material to be cut.